1. Field of the Invention
The disclosures herein generally relate to communication devices, methods for controlling communication devices and storage medium for storing a program causing the control part of a communication device to execute a control method.
2. Description of the Related Art
Historically, as disclosed in Japanese Laid-Open Patent Application No. 2011-35798, a projector which can communicate with external devices via a network comprises three microcomputers: an intelligent main microcomputer controlling a graphic processing and optical system driving part; a sub microcomputer, which works in a stand-by state, controlling an input unit and a display unit such as an operating panel and a remote controller receiver and an RS-232C terminal; and a network microcomputer controlling a network.
In the stand-by state in which the projector does not project an image, the main microcomputer and the network microcomputer are generally turned off while only the sub microcomputer is turned on, thereby reducing power consumption.
In addition, Japanese Laid-Open Patent Application No. 2011-35798 discloses the following configuration in order to simplify a system configuration and to decrease power consumption. The disclosure comprises: a main microcomputer and a network microcomputer having functions to control a network, an input unit, and a display unit and further having a fan control function. The network microcomputer controls the power supply to the main microcomputer at the time of transition to a stand-by state or return to a normal state.
In the configuration using three microcomputers, the network microcomputer has to be switched on in order to use a function using network communication in stand-by state (e.g. a projector control function with the PJLink protocol). The problem with this arrangement is that power consumption cannot be reduced sufficiently.
Also on the configuration using two microcomputers, the power of the network microcomputer having various functions needs to be switched on in the stand-by state; this also gives rise to a problem that the power consumption cannot be reduced sufficiently. Such a problem occurs not only in projectors but also in communication devices that have a function to communicate with an external device via a network. That is, the problem occurs when an attempt is made to reduce power consumption in the stand-by state in which the network communication function is enabled while other functions are suspended to an extent possible.
This invention aims to solve that problem and reduce power consumption in the stand-by state in which a network communication function is enabled on a communication device having communication functions with an external device via a network.